same period; however, liver tissue decay and decline rates are similar. Tc UUle. ences in rate of aecay and decline in both bone and muscle may indicate greater retention ae well as continued uptake of long-lived e . radioactive materials in these tissues. Figure 2 illustrates the rate of decline in the tiseues of fish from Rongelap Island between January 25, 1955 and July 17, 1957. Again it will be noted that the rate of Jecline of radioactivity is somewhat greater in the liver tissue than inbone or muscle. All tissues show a definite increase in radioactivity after the summer of 1956, reaching a relatively higher level than for the same tissues in fish from Kabelle Island, but declining at a more rapid rate after 1956. Decay and decline ratee of radioactivity of muscle and bone tissue from fish from Rongelap Island are approximately the same, decay being Slightly more rapid. The radioactivity in liver tissue declines at a more rapid rate than it decays. Gross Gamma Radtoactivity, 1957 Table 3 contains data on gross levels of gamma radioactivity in the homogenate of many reef fishes collected at Rongelap and Ailinginae Atolls. As with the beta radioactivity, Rongelap Island fish generally had less ganrra radioactivity than fish from either Enibuk or Kabelle Islands. ences were not great between sin.ilar Also differ- species from different isiands. markedly higher amount of radioactivity A was noted again in the liver of